I use a 85 mm Nikon lens for single shot portraits. I've never really done much group photos like a family of 4 or 5. I've noticed in the Pat when I've used my 85 mm lens for a few people, somome is always out if focus. My question is if I'm going to do a family should I use my 35 mm 1.8 or the 85 mm 1.8?
The 35mm lens seems more practical for groups.
You do always want to stand back at least about 7 feet for proper portrait perspective.
For a single portrait, the 85 mm on DX has a field of view about 2x3 feet if at about 11 feet. That seems doable, and very proper.
But 85mm for a group, say about 6x4 feet view on DX, is 21 feet. Not so great. Still, you don't have to use f/1.8. If you provide enough light, you can use f/8 for more depth of field (DOF is also limited when you get too close).
But the 35mm lens, for about 6x4 feet view on DX, is about 9 feet. Again doable.